Conventionally, there has been developed a fiber reinforced resin gear containing glass fibers each having a fixed fiber diameter. The fiber reinforced resin gear has a higher strength than a gear formed using only a resin material and is more light-weighted than a metal-made gear and hence, the fiber reinforced resin gear has been popularly used as power transmission parts of automobiles which aim at the enhancement of fuel consumption and various machines which aim at the reduction of weight thereof (see PTL 1).